Hi, There are lots of posts in this list about MSN messenger but I will try to mention some of them: 1- Firewall client software should be installed on the client computer. 2- Your user must have logged in to the same domain of ISA Server computer and with a username that have permission to use MSN protocol. 3- MSN should be set to not use any proxies (it's optional I think) 4- http://support.microsoft.com/default.aspx?scid=kb;EN-US;q277812 5- http://isaserver.org/pages/games.htm and finally you can have a look at this special article!!! http://isaserver.org/shinder/tutorials/blockim.htm